<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>demo</title>
</head>
<style>
  .box{
    width: 400px;
  }
  .a {
    width: 100px;
    height: 100px;
    background-color: black;
    float: left;
  }
  .b {
    height: 100px;
    overflow: hidden;
    background-color: cornflowerblue;
  }
  .c {
    width: 100px;
    height: 100px;
    background-color: black;
    float: right;
  }
</style>
<body>
  <div class="box">
    <div class="a"></div>
    <div class="c"></div>
    <div class="b"></div>
  </div>
</body>
</html>